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Tethered Hydroplane Classes and British Records

Naviga A3

NAVIGA International Classes. Current Records

A1 up to 3.5cc     1.2kg    Ex Dia 7.0mm Rashid Chabibulin 06/08/2016 213.777kph (132.75mph)
AE Electric          1.2kg  42v Max Oleksi Smolnikov 30/07/2017 233.463kph (144.98mph)
A2 up to 7.5cc     2.0kg   Ex Dia 8.0mm Vladislav Subbotin 26/08/1999 218.871kph (135.92mph)
A3 up to 10cc      2.5kg   Ex Dia 10mm Vladislav Subbotin 05/07/2004 232.259kph (144.23mph)
B1 2.5cc airscrew 0.75kg Ex Dia 5.0mm Babken Shahazizian 30/07/2017 284.360kph (176.58mph)
B1E airscrew       0.75kg  42v Max Farid Ishmetov 30/07/2017 273.556kph (169.87mph)

MPBA 'International' Classes. Current Records

A1 Pete Dirs 13/08/17 122.64 mph
AE     No record established
A2 Roger James 3/08/03 129.30 mph (Set with 6.5cc motor)
A3 Norman Lara 06/07/14 141.70 mph
B1 Jim Free  10/04/00 154.91 mph
B1E     No record established
Pete Dirs Roger James Norman Lara Jim Free

MPBA British Classes. Current Records

Sport 40 E Martin Broad 20/07/14 111.29 mph
Sport 40 IC Angela Gullick 27/08/17 106.77 mph  
B1 Sport Jim Free 28/05/17 128.48 mph 
B Ron Hankins 19/06/16 124.76 mph 
B/S 9lb Stan Poyser (deceased) 02/08/98 96.67 mph
A John Hyder 08/10/00 130.05 mph
A/S Paul Windross 07/07/13 129.33 mph
B/R Ron Hankins 11/09/16 137.88 mph  
Vintage Not applicable to this class. Lambert Trophy awarded for the fastest speed recorded each season
Ron Hankins The late Stan Poyser Angela Gullick

John Hyder

Paul Windross Left: Martin Broad

British Classes

A1              1.2kg  Waterscrew up to 3.5cc. Straight fuel.  *All waterscrew classes must run with silencers*
A1E          1.2kg Electric Max 42V
A2          2.0kg 3.5cc to 7.5cc  Straight fuel
A3            2.5kg 7.5cc to 10cc   Straight fuel
B1            0.75kg 2.5cc airscrew  Straight fuel 5.0mm max exhaust dia
B1E          0.75kg Electric airscrew, max 42v     
Sport 40    4.0lbs 6.5cc side exhaust 2-stroke. 10cc 4-stroke . Commercial components Free fuel
Sport E      4.0lbs 6 cell 22.5v electric
B1 Sport   2.0lbs £90 limit on motor, 5mm exhaust outlet, commercial propellers. Free fuel
B Class     8.0lbs Up to 15cc homebuilt engines.  Free fuel
B/S Class 9.0lbs Steam powered, all up weight not to exceed 9lbs.
A Class    16.0lbs Up to 30cc homebuilt engines.  Free fuel
A/S Class 16.0lbs Steam powered, all up weight not to exceed 16lbs.
B/R            6.0lbs Commercial engines up to 15cc. Free fuel
Vintage Waterscrew or Airscrew, pre 1963 boat or design with engine of contemporary date.
Sport 40 Electric Vintage


On first glance both of these airscrew hydroplanes are very similar. They are both powered by 2.5cc engines, are both about the same weight, the engine mounting being the most obvious difference. One being a side mounted set up, the other being inverted. They are in fact quite different when it comes to power, speed and most definitely cost.

Let us first take the boat at the bottom. This is the open class B1 hydro, built from quite high tech materials such as carbon fibre, Kevlar, alloys of one sort or another, with some lime and balsa. The whole thing is covered in epoxy. The power for this boat comes from a Russian made Cyclon TOP 2.5cc engine costing some £500. Competition fuel is 80%-20% methanol, castor oil mix. For the top boats in the class, speeds of 160-170 mph can be expected.

The top boat is quite a different kettle of fish. This is the B1 Sport where certain elements are "RESTRICTED".

What are these restrictions?

The first thing to remember is that this class is mainly aimed at the beginner in the sport. Materials used in the hull construction are now free, but all parts must easily obtained commercially via local model shop etc. The engine is the area where costs and performance are controlled and has a maximum price of £90, which is reviewed annually and must not be modified. However there is now no restriction on the fuel used . The record for the B1R class, which this replaces is a tad over 120 mph. So there you have it, two boats that on the surface look very much the same, but that are quite different.

Thanks to Jim Free for this description of the two airscrew classes

Commercial engine 'Sport 40' 15cc from castings 'B' 30cc from bar stock 'A' Poppet valve flash steamer 'A/S'

Records are correct at 01/01/18. Thanks to Norman Lara. Photos Jim Free, OTW, Sonia and Tony Collins.